不同围封方式初期川西北高寒草甸的群落结构和稳定性

Effects of different enclosure methods on early community vegetation structure and stability of alpine meadows in northwest Sichuan

为探讨川西北高寒草甸的适宜管理措施,本研究以禁牧、限牧(生长季禁牧+非生长季放牧)、草畜平衡管理下的高寒草甸典型样地为研究对象,以围栏外的退化草地为对照。采用野外调查与室内分析相结合的方法,分析不同围封方式初期川西北高寒草甸植物群落物种多样性、稳定性及二者之间的关系,初步确定适宜的草地管理模式。结果表明:1)草畜平衡、限牧、禁牧3种围封管理初期,植物群落以垂穗披碱草(Elymus nutans)等禾草为优势种,其重要值分别为9.14、13.52和8.17,而退化草地群落无绝对优势种,以蕨麻(Potentilla anserina)、草玉梅(Anemone rivularis)、淡黄香青(Anaphalis flavescens)为主要植物种。2)围栏措施增加了群落物种多样性,禁牧管理下群落物种多样性最高,草畜平衡管理下群落物种多样性最低,而退化草地群落的Simpson多样性指数和Pielou均匀度指数稍高于限牧草地。3)各样地群落稳定性大小表现为限牧>草畜平衡>禁牧>退化,合理放牧可提高草地稳定性。4)群落物种多样性与稳定性整体呈负相关关系,物种多样性主要受物种的种类和数量分布影响,而群落稳定性则与优势种的稳定性密切相关。从植物群落结构和稳定性综合考虑,禁牧和限牧管理是川西北高寒草甸植被恢复和重建的有效措施。

This research explores suitable management measures for alpine meadows in northwestern Sichuan.In this study,grazing prohibition and grazing restrictions(grazing prohibition in growing season+grazing in non-growing season)and typical alpine meadow plots under the management of forage and animal husbandry were used as the research object for this research.Degraded grassland vegetation outside the fence was used to create a control group.Using a combination of field surveys and lab-based analyses,species diversity and stability of the alpine meadow plant community in Northwest Sichuan was examined.This research explored the relationship between species diversity and plant community stability immediately following enclosure of research plots to determine preliminary recommendations for an appropriate grassland management model.The results showed the following:1)In the initial stage of implementation of the three enclosure management methods,grasses such as Elymus nutans are the dominant species in the plant community,with important values of 9.14,13.52,and 8.17,respectively.No absolute dominant species were recorded in the degraded grassland community,with Potentilla anserina,Anemone rivularis,and Anaphalis flavescens being the main plant species observed.2)Provision of fencing increased community species diversity.Sites where prohibition of grazing had been implemented had the highest species diversity.The lowest species diversity was recorded for the forage-livestock balance plant community.Simpson’s diversity index and Pielou evenness index of were slightly higher in the degraded grassland communities in comparison to grasslands where grazing was restricted.3)The stability of the community in each plot is expressed as grazing restriction>forage-livestock balance>grazing prohibition>degeneration.Reasonable grazing can therefore improve grassland stability.4)The relationship between community species diversity and stability was found to be negative.Species diversity is mainly affected by the type and quantity distribution of species,while community stability is closely related to the stability of dominant species.Therefore,taking into account the structure and stability of the plant community,grazing prohibition and grazing restriction management are effective measures for the ecological restoration of alpine meadow vegetation in northwest Sichuan.